1. Field of the Invention
The present invention relates to an optical sheet, a backlight unit including the optical sheet, and a liquid crystal display including the backlight unit, all for the use within a display device such as a television, a computer, a personal data assistant, a mobile telephone, a vehicle (e.g., automobile or airplane) terminal such as a navigation unit or another device.
2. Description of the Related Art
Recently, the types of displays capable of visually displaying information of various electrical signals has rapidly grown. Various kinds of flat panel displays having excellent characteristics such as thin profile, lightness in weight, and low power consumption have been introduced. Accordingly, cathode ray tubes (CRT) are being rapidly replaced by the flat panel displays as the device of choice by the consumer and industry.
The typical flat panel displays include, for example, a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), and an electroluminescence display (ELD). The conventional liquid crystal display is actively used as display panels of notebook computers, monitors of personal computers, televisions, and other monitors because of ability to provide a high contrast ratio and excellent display characteristics of a still and a moving picture.
The liquid crystal display includes a liquid crystal display panel displaying an image and a backlight unit that is positioned under the liquid crystal display panel to provide the liquid crystal display panel with light.
The backlight unit includes a light source and an optical sheet. The optical sheet typically includes a diffusion sheet, a prism sheet, or a protective sheet.
If the uniformity of a luminance of light provided by the backlight unit to the liquid crystal display panel is reduced, the display quality of the liquid crystal display is reduced. In the related art, the conventional diffusion sheet allows the light to be uniformly diffused over the entire surface of a display area of the liquid crystal display panel so as to prevent a reduction in the luminance uniformity of the light. However, it is difficult to secure a high optical diffusion rate as well as the luminance uniformity using only the conventional diffusion sheet.